python/ovs/db/idl.py: Transaction._substitute doesn't handle list/tuple

python/ovs/db/idl.py: Transaction._substitute doesn't handle list/tuple

Since Transaction._substitute doesn't substitute elements of list/tuple,
setting list references results in transaction error. Teach it such case.

Example:
{"op": "update",
 "row":{"bridges":["set",[["uuid",
                           "1f42bc19-307f-42e7-a9c0-c12178bd8b51"],
                          ["uuid",
                           "f97e0c76-7146-489d-9bed-29bc704f65fe"]]]},
 "table": "Open_vSwitch",
 "where":[["_uuid", "==", ["uuid",
                           "20c2a046-ae7e-4453-a576-11034db24985"]]]}

In the above case, uuid in "row" aren't replaced by "named-uuid" because
the function doesn't look into elements of lists.
When list/tuple is found, look into elements recursively.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Ben Pfaff <blp@nicira.com>